Chen Mengyu, Chen Xingtong, Ma Wenchen, Sun Xiaojuan, Wu Longjia, Lin Xiongfeng, Yang Yixing, Li Rui, Shen Dongyang, Chen Yu, Chen Song
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, 199 Ren'ai Road, Suzhou Industrial Park, Suzhou 215123, Jiangsu, China.
School of Optoelectronic Science and Engineering, Soochow University, 1 Shizi Street, Gusu District, Suzhou 215006, Jiangsu, China.
ACS Nano. 2022 Jun 28;16(6):9631-9639. doi: 10.1021/acsnano.2c02912. Epub 2022 Jun 7.
ZnO-based electron-transporting layers (ETLs) have been universally used in quantum-dot light-emitting diodes (QLEDs) for high performance. The active surface chemistry of ZnO nanoparticles (NPs), however, leads to QLEDs with positive aging and unacceptably poor shelf stability. SnO is a promising candidate for ETLs with less reactivity, but NP agglomeration in nonionic solvents makes the conventional device structure abandoned, resulting in QLEDs with extremely low operational lifetimes. The large barrier for electron injection also limits the electroluminescence efficiency. Here, we report one solution to all the above-mentioned problems. Owing to the strong HO-SnO coordination and the steric effect provided by the hydrocarbon groups, tetramethylammonium hydroxide can stabilize SnO NPs in alcohol, while its intrinsic dipole induces a favorable electronic-level shift for charge injection. The SnO-based devices, with the conventional structure, exhibit not only the most efficient electroluminescence among ZnO-free QLEDs but also an operational lifetime () over 3200 h at 1000 cd m, which is comparable with that of state-of-the-art ZnO-based devices. More importantly, the superior shelf stability means that the TMAH-SnO NPs are promising to enable QLEDs with real stability.
基于氧化锌的电子传输层（ETL）已被广泛应用于高性能量子点发光二极管（QLED）中。然而，氧化锌纳米颗粒（NP）的活性表面化学性质导致QLED出现正向老化且储存稳定性差得令人无法接受的问题。氧化锡是一种反应性较低的ETL的有前景的候选材料，但在非离子溶剂中NP团聚使得传统器件结构被摒弃，导致QLED的工作寿命极低。电子注入的大势垒也限制了电致发光效率。在此，我们报告了一种解决上述所有问题的方法。由于强的HO-SnO配位以及烃基提供的空间效应，氢氧化四甲铵可以在醇中稳定SnO NP，同时其固有偶极会引起有利于电荷注入的电子能级移动。具有传统结构的基于SnO的器件不仅在无ZnO的QLED中表现出最高效的电致发光，而且在1000 cd m下的工作寿命超过3200小时，这与最先进的基于ZnO的器件相当。更重要的是，优异的储存稳定性意味着氢氧化四甲铵-SnO NP有望实现具有真正稳定性的QLED。
